Automatic choke



Aug. 15, 1950 M. J. KITTLER EI'AL AUTOMATIC CHOKE Filed Jan. 23, 1947 HBMJLQ Mel Ki filer INVENTOR.

F7 7 TOP/YE Y Patented Aug. 15, 1950 AUTOMATIC CHOKE Milton J. Kittler and Harry B. Medley, Detroit, Mich., assignors to George M. Holley and Earl Holley Application January 23, 1947, Serial No. 723,816

1 Claim. l

The object of this invention is to reduce the cost of an automatic choke for an automobile engme.

Fig. 1 shows the position of the essential elements of our invention when the engine is running and the throttle is closed.

Fig. 2 shows the position of the choke when the throttle is open and the engine is cold.

In the figures, I is the air entrance, I2 is the throttle in the mixture outlet. i4 is the choke control rod. This rod has a fast idle surface l6 and a normal slow idle surface l8. In the position shown in Fig. 1, with the throttle lever 28 closed, the adjustable idle screw 50 engages with the fast idle surface I6.

A helical thermostat (Fig. 2) at one end engages with a stop 65 and at the other end with a choke shaft 22 which carries the choke-valve 42 inside the air entrance H), and outside it carries an arm with two jaws 24 and 64 which together form a claw. Inside the jaws of this claw is an ear 26 projecting from the control rod I4.

The throttle lever 28 carries two steps 30 and 32. The sto 30 engages with a second ear 34 also projecting from .the control rod [4. The stop 32 engages with a stationary stop 36 and limits the wide open position of the throttle l2 carried on the throttle shaft 52.

A vacuum piston 38 reciprocates inside a vacuum cylinder 40 and when engine suction is applied through a passage 48 it pulls the choke valve 42 into a somewhat openposition against the tension of the thermostatic spring 20 through the linkage 44. A passage 48 admits the suction on the engine side of the throttle l2 to the underside of the piston 40. The leakage of air around the piston creates an atmospheric depression The throttle in Fig. 1 is shown almost closed. The fast idle surface I6 then keeps the throttle slightly open.

The moment the engine fires the piston 38 is drawn down. A choke shaft 22 is rotated anticlockwise. Choke valve 42 is then opened slightly. When the throttle lever 28 is rotated clockwise so as to open the throttle II to the throttle stop 30 engages with the second car 34 and the first ear 26 engages with the jaw 64. The choke valve 42 is again opened slightly.

When the thermostat 20 expands, responsive to the heat drawn up through the pipe 46, the ear 26 is carried up by the jaw 24.

The rod i4 thereupon rises. The normal idle surface If! then takes the place of the fast idle surface IS. The adjustable stop 50 can then engage with the surface 58 and a normal, that is to say a slow idle, is possible.

The ordinary float chamber 56 is shown and the ordinary venturi E8 is shown but the details of the fuel nozzle are omitted to avoid confusion.

What we claim is:

In an automatic choke mechanism for a carburetor having a throttle valve, a throttle shaft therefor, a choke valve, an off-center choke shaft therefor parallel with the throttle shaft, heat responsive means engaging with and opening said choke valve when hot, an engine suction responsive piston engaging with and opening said choke and choke shaft whenever an appreciable engine suction exists below the throttle, the improvement which consists of a choke lever mounted on said choke shaft having an opening formed by jaws, a choke control rod having forked ends slidably mounted on and guided by said two parallel shafts, means therefor made integral therewith and comprising, two surfaces on said control rod, one for fast idle the other for normal idle speeds, an adjustable stop on said throttle lever adapted to engage with one of the two surfaces, a first ear projecting from the control rod, said ear engaging loosely within the jaws of the choke shaft lever so that movement of the control rod is communicated to the choke shaft and movement of the choke shaft is communicated to the control rod, a second ear projecting from the control rod, a stop on the throttle lever engaging'with said second ear when the throttle is almost wide open whereby when the throttle lever is opened wide the choke valve is opened slightly and when the choke valve is opened towards its wide open position by the heat responsive means the normal idle surface is moved so as to take the place of the fast idle surface with reference to the adjustable stop on said throttle lever.

MILTON J. KITTLER.

HARRY B. MEDLEY.

REFERENCES CITED UNITED STATES PATENTS Name Date Hunt Sept. 24, 1940 Number 

